The present invention relates to a semiconductor arrangement having a MOSFET structure and a zener device provided between the gate and drain of the MOSFET structure. In this case, MOSFET structure is to be understood primarily as a MOSFET. However, an IGBT (insulated gate bipolar transistor), for example, is also regarded as such a MOSFET structure. Generally, however, any semiconductor component in which a current flow is controlled by means of an insulated control electrode has such a MOSFET structure.
As is known, in order to increase the robustness of power MOSFETS, it is possible to use the so-called “active zenering” (active zener function), in the case of which, as is illustrated in FIG. 1, a zener diode Z1 is located between a control electrode G and a drain electrode D. A diode D1 may also be provided in a manner reverse-connected in series with said zener diode Z1, the diodes Z1 and D1 being formed by corresponding pn junctions. One example of such active zenering is the so-called PROFET, in which a protective diode is provided between the gate electrode and drain electrode.
The effect of the active zenering is that in the event of an increased voltage that is present at the drain electrode D and exceeds the zener voltage of the zener diode Z1, the MOSFET is switched on again and a current flow occurs between the source electrode S and drain electrode D.
To date, active zenering in MOSFETs has been realized by means of a separate Zener diode or else in integrated form. However, the outlay for this is not inconsiderable since the formation of the zener diode requires additional area on the integrated circuit besides further doping steps.